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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network151.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
151.0.0.0
Broadcast address
151.63.255.255
First usable
151.0.0.1
Last usable
151.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
B (default /16)
As numbers
Hex 97000000 · Integer 2533359616 to 2537553919
Reverse DNS zones
0.151.in-addr.arpa
1.151.in-addr.arpa
2.151.in-addr.arpa
3.151.in-addr.arpa
4.151.in-addr.arpa
5.151.in-addr.arpa
6.151.in-addr.arpa
7.151.in-addr.arpa
8.151.in-addr.arpa
9.151.in-addr.arpa
10.151.in-addr.arpa
11.151.in-addr.arpa
12.151.in-addr.arpa
13.151.in-addr.arpa
14.151.in-addr.arpa
15.151.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010111.00000000.00000000.00000000151.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network10010111.00000000.00000000.00000000151.0.0.0
Broadcast10010111.00111111.11111111.11111111151.63.255.255
Split into smaller subnets/21
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

151.0.0.0/10 makes 2,048 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1151.0.0.0/21151.0.0.1 to 151.0.7.254151.0.7.2552,046
2151.0.8.0/21151.0.8.1 to 151.0.15.254151.0.15.2552,046
3151.0.16.0/21151.0.16.1 to 151.0.23.254151.0.23.2552,046
4151.0.24.0/21151.0.24.1 to 151.0.31.254151.0.31.2552,046
5151.0.32.0/21151.0.32.1 to 151.0.39.254151.0.39.2552,046
6151.0.40.0/21151.0.40.1 to 151.0.47.254151.0.47.2552,046
7151.0.48.0/21151.0.48.1 to 151.0.55.254151.0.55.2552,046
8151.0.56.0/21151.0.56.1 to 151.0.63.254151.0.63.2552,046
9151.0.64.0/21151.0.64.1 to 151.0.71.254151.0.71.2552,046
10151.0.72.0/21151.0.72.1 to 151.0.79.254151.0.79.2552,046
11151.0.80.0/21151.0.80.1 to 151.0.87.254151.0.87.2552,046
12151.0.88.0/21151.0.88.1 to 151.0.95.254151.0.95.2552,046
13151.0.96.0/21151.0.96.1 to 151.0.103.254151.0.103.2552,046
14151.0.104.0/21151.0.104.1 to 151.0.111.254151.0.111.2552,046
15151.0.112.0/21151.0.112.1 to 151.0.119.254151.0.119.2552,046
16151.0.120.0/21151.0.120.1 to 151.0.127.254151.0.127.2552,046
17151.0.128.0/21151.0.128.1 to 151.0.135.254151.0.135.2552,046
18151.0.136.0/21151.0.136.1 to 151.0.143.254151.0.143.2552,046
19151.0.144.0/21151.0.144.1 to 151.0.151.254151.0.151.2552,046
20151.0.152.0/21151.0.152.1 to 151.0.159.254151.0.159.2552,046
21151.0.160.0/21151.0.160.1 to 151.0.167.254151.0.167.2552,046
22151.0.168.0/21151.0.168.1 to 151.0.175.254151.0.175.2552,046
23151.0.176.0/21151.0.176.1 to 151.0.183.254151.0.183.2552,046
24151.0.184.0/21151.0.184.1 to 151.0.191.254151.0.191.2552,046
25151.0.192.0/21151.0.192.1 to 151.0.199.254151.0.199.2552,046
26151.0.200.0/21151.0.200.1 to 151.0.207.254151.0.207.2552,046
27151.0.208.0/21151.0.208.1 to 151.0.215.254151.0.215.2552,046
28151.0.216.0/21151.0.216.1 to 151.0.223.254151.0.223.2552,046
29151.0.224.0/21151.0.224.1 to 151.0.231.254151.0.231.2552,046
30151.0.232.0/21151.0.232.1 to 151.0.239.254151.0.239.2552,046
31151.0.240.0/21151.0.240.1 to 151.0.247.254151.0.247.2552,046
32151.0.248.0/21151.0.248.1 to 151.0.255.254151.0.255.2552,046
33151.1.0.0/21151.1.0.1 to 151.1.7.254151.1.7.2552,046
34151.1.8.0/21151.1.8.1 to 151.1.15.254151.1.15.2552,046
35151.1.16.0/21151.1.16.1 to 151.1.23.254151.1.23.2552,046
36151.1.24.0/21151.1.24.1 to 151.1.31.254151.1.31.2552,046
37151.1.32.0/21151.1.32.1 to 151.1.39.254151.1.39.2552,046
38151.1.40.0/21151.1.40.1 to 151.1.47.254151.1.47.2552,046
39151.1.48.0/21151.1.48.1 to 151.1.55.254151.1.55.2552,046
40151.1.56.0/21151.1.56.1 to 151.1.63.254151.1.63.2552,046
41151.1.64.0/21151.1.64.1 to 151.1.71.254151.1.71.2552,046
42151.1.72.0/21151.1.72.1 to 151.1.79.254151.1.79.2552,046
43151.1.80.0/21151.1.80.1 to 151.1.87.254151.1.87.2552,046
44151.1.88.0/21151.1.88.1 to 151.1.95.254151.1.95.2552,046
45151.1.96.0/21151.1.96.1 to 151.1.103.254151.1.103.2552,046
46151.1.104.0/21151.1.104.1 to 151.1.111.254151.1.111.2552,046
47151.1.112.0/21151.1.112.1 to 151.1.119.254151.1.119.2552,046
48151.1.120.0/21151.1.120.1 to 151.1.127.254151.1.127.2552,046
49151.1.128.0/21151.1.128.1 to 151.1.135.254151.1.135.2552,046
50151.1.136.0/21151.1.136.1 to 151.1.143.254151.1.143.2552,046
51151.1.144.0/21151.1.144.1 to 151.1.151.254151.1.151.2552,046
52151.1.152.0/21151.1.152.1 to 151.1.159.254151.1.159.2552,046
53151.1.160.0/21151.1.160.1 to 151.1.167.254151.1.167.2552,046
54151.1.168.0/21151.1.168.1 to 151.1.175.254151.1.175.2552,046
55151.1.176.0/21151.1.176.1 to 151.1.183.254151.1.183.2552,046
56151.1.184.0/21151.1.184.1 to 151.1.191.254151.1.191.2552,046
57151.1.192.0/21151.1.192.1 to 151.1.199.254151.1.199.2552,046
58151.1.200.0/21151.1.200.1 to 151.1.207.254151.1.207.2552,046
59151.1.208.0/21151.1.208.1 to 151.1.215.254151.1.215.2552,046
60151.1.216.0/21151.1.216.1 to 151.1.223.254151.1.223.2552,046
61151.1.224.0/21151.1.224.1 to 151.1.231.254151.1.231.2552,046
62151.1.232.0/21151.1.232.1 to 151.1.239.254151.1.239.2552,046
63151.1.240.0/21151.1.240.1 to 151.1.247.254151.1.247.2552,046
64151.1.248.0/21151.1.248.1 to 151.1.255.254151.1.255.2552,046
65151.2.0.0/21151.2.0.1 to 151.2.7.254151.2.7.2552,046
66151.2.8.0/21151.2.8.1 to 151.2.15.254151.2.15.2552,046
67151.2.16.0/21151.2.16.1 to 151.2.23.254151.2.23.2552,046
68151.2.24.0/21151.2.24.1 to 151.2.31.254151.2.31.2552,046
69151.2.32.0/21151.2.32.1 to 151.2.39.254151.2.39.2552,046
70151.2.40.0/21151.2.40.1 to 151.2.47.254151.2.47.2552,046
71151.2.48.0/21151.2.48.1 to 151.2.55.254151.2.55.2552,046
72151.2.56.0/21151.2.56.1 to 151.2.63.254151.2.63.2552,046
73151.2.64.0/21151.2.64.1 to 151.2.71.254151.2.71.2552,046
74151.2.72.0/21151.2.72.1 to 151.2.79.254151.2.79.2552,046
75151.2.80.0/21151.2.80.1 to 151.2.87.254151.2.87.2552,046
76151.2.88.0/21151.2.88.1 to 151.2.95.254151.2.95.2552,046
77151.2.96.0/21151.2.96.1 to 151.2.103.254151.2.103.2552,046
78151.2.104.0/21151.2.104.1 to 151.2.111.254151.2.111.2552,046
79151.2.112.0/21151.2.112.1 to 151.2.119.254151.2.119.2552,046
80151.2.120.0/21151.2.120.1 to 151.2.127.254151.2.127.2552,046
81151.2.128.0/21151.2.128.1 to 151.2.135.254151.2.135.2552,046
82151.2.136.0/21151.2.136.1 to 151.2.143.254151.2.143.2552,046
83151.2.144.0/21151.2.144.1 to 151.2.151.254151.2.151.2552,046
84151.2.152.0/21151.2.152.1 to 151.2.159.254151.2.159.2552,046
85151.2.160.0/21151.2.160.1 to 151.2.167.254151.2.167.2552,046
86151.2.168.0/21151.2.168.1 to 151.2.175.254151.2.175.2552,046
87151.2.176.0/21151.2.176.1 to 151.2.183.254151.2.183.2552,046
88151.2.184.0/21151.2.184.1 to 151.2.191.254151.2.191.2552,046
89151.2.192.0/21151.2.192.1 to 151.2.199.254151.2.199.2552,046
90151.2.200.0/21151.2.200.1 to 151.2.207.254151.2.207.2552,046
91151.2.208.0/21151.2.208.1 to 151.2.215.254151.2.215.2552,046
92151.2.216.0/21151.2.216.1 to 151.2.223.254151.2.223.2552,046
93151.2.224.0/21151.2.224.1 to 151.2.231.254151.2.231.2552,046
94151.2.232.0/21151.2.232.1 to 151.2.239.254151.2.239.2552,046
95151.2.240.0/21151.2.240.1 to 151.2.247.254151.2.247.2552,046
96151.2.248.0/21151.2.248.1 to 151.2.255.254151.2.255.2552,046
97151.3.0.0/21151.3.0.1 to 151.3.7.254151.3.7.2552,046
98151.3.8.0/21151.3.8.1 to 151.3.15.254151.3.15.2552,046
99151.3.16.0/21151.3.16.1 to 151.3.23.254151.3.23.2552,046
100151.3.24.0/21151.3.24.1 to 151.3.31.254151.3.31.2552,046
101151.3.32.0/21151.3.32.1 to 151.3.39.254151.3.39.2552,046
102151.3.40.0/21151.3.40.1 to 151.3.47.254151.3.47.2552,046
103151.3.48.0/21151.3.48.1 to 151.3.55.254151.3.55.2552,046
104151.3.56.0/21151.3.56.1 to 151.3.63.254151.3.63.2552,046
105151.3.64.0/21151.3.64.1 to 151.3.71.254151.3.71.2552,046
106151.3.72.0/21151.3.72.1 to 151.3.79.254151.3.79.2552,046
107151.3.80.0/21151.3.80.1 to 151.3.87.254151.3.87.2552,046
108151.3.88.0/21151.3.88.1 to 151.3.95.254151.3.95.2552,046
109151.3.96.0/21151.3.96.1 to 151.3.103.254151.3.103.2552,046
110151.3.104.0/21151.3.104.1 to 151.3.111.254151.3.111.2552,046
111151.3.112.0/21151.3.112.1 to 151.3.119.254151.3.119.2552,046
112151.3.120.0/21151.3.120.1 to 151.3.127.254151.3.127.2552,046
113151.3.128.0/21151.3.128.1 to 151.3.135.254151.3.135.2552,046
114151.3.136.0/21151.3.136.1 to 151.3.143.254151.3.143.2552,046
115151.3.144.0/21151.3.144.1 to 151.3.151.254151.3.151.2552,046
116151.3.152.0/21151.3.152.1 to 151.3.159.254151.3.159.2552,046
117151.3.160.0/21151.3.160.1 to 151.3.167.254151.3.167.2552,046
118151.3.168.0/21151.3.168.1 to 151.3.175.254151.3.175.2552,046
119151.3.176.0/21151.3.176.1 to 151.3.183.254151.3.183.2552,046
120151.3.184.0/21151.3.184.1 to 151.3.191.254151.3.191.2552,046
121151.3.192.0/21151.3.192.1 to 151.3.199.254151.3.199.2552,046
122151.3.200.0/21151.3.200.1 to 151.3.207.254151.3.207.2552,046
123151.3.208.0/21151.3.208.1 to 151.3.215.254151.3.215.2552,046
124151.3.216.0/21151.3.216.1 to 151.3.223.254151.3.223.2552,046
125151.3.224.0/21151.3.224.1 to 151.3.231.254151.3.231.2552,046
126151.3.232.0/21151.3.232.1 to 151.3.239.254151.3.239.2552,046
127151.3.240.0/21151.3.240.1 to 151.3.247.254151.3.247.2552,046
128151.3.248.0/21151.3.248.1 to 151.3.255.254151.3.255.2552,046
129151.4.0.0/21151.4.0.1 to 151.4.7.254151.4.7.2552,046
130151.4.8.0/21151.4.8.1 to 151.4.15.254151.4.15.2552,046
131151.4.16.0/21151.4.16.1 to 151.4.23.254151.4.23.2552,046
132151.4.24.0/21151.4.24.1 to 151.4.31.254151.4.31.2552,046
133151.4.32.0/21151.4.32.1 to 151.4.39.254151.4.39.2552,046
134151.4.40.0/21151.4.40.1 to 151.4.47.254151.4.47.2552,046
135151.4.48.0/21151.4.48.1 to 151.4.55.254151.4.55.2552,046
136151.4.56.0/21151.4.56.1 to 151.4.63.254151.4.63.2552,046
137151.4.64.0/21151.4.64.1 to 151.4.71.254151.4.71.2552,046
138151.4.72.0/21151.4.72.1 to 151.4.79.254151.4.79.2552,046
139151.4.80.0/21151.4.80.1 to 151.4.87.254151.4.87.2552,046
140151.4.88.0/21151.4.88.1 to 151.4.95.254151.4.95.2552,046
141151.4.96.0/21151.4.96.1 to 151.4.103.254151.4.103.2552,046
142151.4.104.0/21151.4.104.1 to 151.4.111.254151.4.111.2552,046
143151.4.112.0/21151.4.112.1 to 151.4.119.254151.4.119.2552,046
144151.4.120.0/21151.4.120.1 to 151.4.127.254151.4.127.2552,046
145151.4.128.0/21151.4.128.1 to 151.4.135.254151.4.135.2552,046
146151.4.136.0/21151.4.136.1 to 151.4.143.254151.4.143.2552,046
147151.4.144.0/21151.4.144.1 to 151.4.151.254151.4.151.2552,046
148151.4.152.0/21151.4.152.1 to 151.4.159.254151.4.159.2552,046
149151.4.160.0/21151.4.160.1 to 151.4.167.254151.4.167.2552,046
150151.4.168.0/21151.4.168.1 to 151.4.175.254151.4.175.2552,046
151151.4.176.0/21151.4.176.1 to 151.4.183.254151.4.183.2552,046
152151.4.184.0/21151.4.184.1 to 151.4.191.254151.4.191.2552,046
153151.4.192.0/21151.4.192.1 to 151.4.199.254151.4.199.2552,046
154151.4.200.0/21151.4.200.1 to 151.4.207.254151.4.207.2552,046
155151.4.208.0/21151.4.208.1 to 151.4.215.254151.4.215.2552,046
156151.4.216.0/21151.4.216.1 to 151.4.223.254151.4.223.2552,046
157151.4.224.0/21151.4.224.1 to 151.4.231.254151.4.231.2552,046
158151.4.232.0/21151.4.232.1 to 151.4.239.254151.4.239.2552,046
159151.4.240.0/21151.4.240.1 to 151.4.247.254151.4.247.2552,046
160151.4.248.0/21151.4.248.1 to 151.4.255.254151.4.255.2552,046
161151.5.0.0/21151.5.0.1 to 151.5.7.254151.5.7.2552,046
162151.5.8.0/21151.5.8.1 to 151.5.15.254151.5.15.2552,046
163151.5.16.0/21151.5.16.1 to 151.5.23.254151.5.23.2552,046
164151.5.24.0/21151.5.24.1 to 151.5.31.254151.5.31.2552,046
165151.5.32.0/21151.5.32.1 to 151.5.39.254151.5.39.2552,046
166151.5.40.0/21151.5.40.1 to 151.5.47.254151.5.47.2552,046
167151.5.48.0/21151.5.48.1 to 151.5.55.254151.5.55.2552,046
168151.5.56.0/21151.5.56.1 to 151.5.63.254151.5.63.2552,046
169151.5.64.0/21151.5.64.1 to 151.5.71.254151.5.71.2552,046
170151.5.72.0/21151.5.72.1 to 151.5.79.254151.5.79.2552,046
171151.5.80.0/21151.5.80.1 to 151.5.87.254151.5.87.2552,046
172151.5.88.0/21151.5.88.1 to 151.5.95.254151.5.95.2552,046
173151.5.96.0/21151.5.96.1 to 151.5.103.254151.5.103.2552,046
174151.5.104.0/21151.5.104.1 to 151.5.111.254151.5.111.2552,046
175151.5.112.0/21151.5.112.1 to 151.5.119.254151.5.119.2552,046
176151.5.120.0/21151.5.120.1 to 151.5.127.254151.5.127.2552,046
177151.5.128.0/21151.5.128.1 to 151.5.135.254151.5.135.2552,046
178151.5.136.0/21151.5.136.1 to 151.5.143.254151.5.143.2552,046
179151.5.144.0/21151.5.144.1 to 151.5.151.254151.5.151.2552,046
180151.5.152.0/21151.5.152.1 to 151.5.159.254151.5.159.2552,046
181151.5.160.0/21151.5.160.1 to 151.5.167.254151.5.167.2552,046
182151.5.168.0/21151.5.168.1 to 151.5.175.254151.5.175.2552,046
183151.5.176.0/21151.5.176.1 to 151.5.183.254151.5.183.2552,046
184151.5.184.0/21151.5.184.1 to 151.5.191.254151.5.191.2552,046
185151.5.192.0/21151.5.192.1 to 151.5.199.254151.5.199.2552,046
186151.5.200.0/21151.5.200.1 to 151.5.207.254151.5.207.2552,046
187151.5.208.0/21151.5.208.1 to 151.5.215.254151.5.215.2552,046
188151.5.216.0/21151.5.216.1 to 151.5.223.254151.5.223.2552,046
189151.5.224.0/21151.5.224.1 to 151.5.231.254151.5.231.2552,046
190151.5.232.0/21151.5.232.1 to 151.5.239.254151.5.239.2552,046
191151.5.240.0/21151.5.240.1 to 151.5.247.254151.5.247.2552,046
192151.5.248.0/21151.5.248.1 to 151.5.255.254151.5.255.2552,046
193151.6.0.0/21151.6.0.1 to 151.6.7.254151.6.7.2552,046
194151.6.8.0/21151.6.8.1 to 151.6.15.254151.6.15.2552,046
195151.6.16.0/21151.6.16.1 to 151.6.23.254151.6.23.2552,046
196151.6.24.0/21151.6.24.1 to 151.6.31.254151.6.31.2552,046
197151.6.32.0/21151.6.32.1 to 151.6.39.254151.6.39.2552,046
198151.6.40.0/21151.6.40.1 to 151.6.47.254151.6.47.2552,046
199151.6.48.0/21151.6.48.1 to 151.6.55.254151.6.55.2552,046
200151.6.56.0/21151.6.56.1 to 151.6.63.254151.6.63.2552,046
201151.6.64.0/21151.6.64.1 to 151.6.71.254151.6.71.2552,046
202151.6.72.0/21151.6.72.1 to 151.6.79.254151.6.79.2552,046
203151.6.80.0/21151.6.80.1 to 151.6.87.254151.6.87.2552,046
204151.6.88.0/21151.6.88.1 to 151.6.95.254151.6.95.2552,046
205151.6.96.0/21151.6.96.1 to 151.6.103.254151.6.103.2552,046
206151.6.104.0/21151.6.104.1 to 151.6.111.254151.6.111.2552,046
207151.6.112.0/21151.6.112.1 to 151.6.119.254151.6.119.2552,046
208151.6.120.0/21151.6.120.1 to 151.6.127.254151.6.127.2552,046
209151.6.128.0/21151.6.128.1 to 151.6.135.254151.6.135.2552,046
210151.6.136.0/21151.6.136.1 to 151.6.143.254151.6.143.2552,046
211151.6.144.0/21151.6.144.1 to 151.6.151.254151.6.151.2552,046
212151.6.152.0/21151.6.152.1 to 151.6.159.254151.6.159.2552,046
213151.6.160.0/21151.6.160.1 to 151.6.167.254151.6.167.2552,046
214151.6.168.0/21151.6.168.1 to 151.6.175.254151.6.175.2552,046
215151.6.176.0/21151.6.176.1 to 151.6.183.254151.6.183.2552,046
216151.6.184.0/21151.6.184.1 to 151.6.191.254151.6.191.2552,046
217151.6.192.0/21151.6.192.1 to 151.6.199.254151.6.199.2552,046
218151.6.200.0/21151.6.200.1 to 151.6.207.254151.6.207.2552,046
219151.6.208.0/21151.6.208.1 to 151.6.215.254151.6.215.2552,046
220151.6.216.0/21151.6.216.1 to 151.6.223.254151.6.223.2552,046
221151.6.224.0/21151.6.224.1 to 151.6.231.254151.6.231.2552,046
222151.6.232.0/21151.6.232.1 to 151.6.239.254151.6.239.2552,046
223151.6.240.0/21151.6.240.1 to 151.6.247.254151.6.247.2552,046
224151.6.248.0/21151.6.248.1 to 151.6.255.254151.6.255.2552,046
225151.7.0.0/21151.7.0.1 to 151.7.7.254151.7.7.2552,046
226151.7.8.0/21151.7.8.1 to 151.7.15.254151.7.15.2552,046
227151.7.16.0/21151.7.16.1 to 151.7.23.254151.7.23.2552,046
228151.7.24.0/21151.7.24.1 to 151.7.31.254151.7.31.2552,046
229151.7.32.0/21151.7.32.1 to 151.7.39.254151.7.39.2552,046
230151.7.40.0/21151.7.40.1 to 151.7.47.254151.7.47.2552,046
231151.7.48.0/21151.7.48.1 to 151.7.55.254151.7.55.2552,046
232151.7.56.0/21151.7.56.1 to 151.7.63.254151.7.63.2552,046
233151.7.64.0/21151.7.64.1 to 151.7.71.254151.7.71.2552,046
234151.7.72.0/21151.7.72.1 to 151.7.79.254151.7.79.2552,046
235151.7.80.0/21151.7.80.1 to 151.7.87.254151.7.87.2552,046
236151.7.88.0/21151.7.88.1 to 151.7.95.254151.7.95.2552,046
237151.7.96.0/21151.7.96.1 to 151.7.103.254151.7.103.2552,046
238151.7.104.0/21151.7.104.1 to 151.7.111.254151.7.111.2552,046
239151.7.112.0/21151.7.112.1 to 151.7.119.254151.7.119.2552,046
240151.7.120.0/21151.7.120.1 to 151.7.127.254151.7.127.2552,046
241151.7.128.0/21151.7.128.1 to 151.7.135.254151.7.135.2552,046
242151.7.136.0/21151.7.136.1 to 151.7.143.254151.7.143.2552,046
243151.7.144.0/21151.7.144.1 to 151.7.151.254151.7.151.2552,046
244151.7.152.0/21151.7.152.1 to 151.7.159.254151.7.159.2552,046
245151.7.160.0/21151.7.160.1 to 151.7.167.254151.7.167.2552,046
246151.7.168.0/21151.7.168.1 to 151.7.175.254151.7.175.2552,046
247151.7.176.0/21151.7.176.1 to 151.7.183.254151.7.183.2552,046
248151.7.184.0/21151.7.184.1 to 151.7.191.254151.7.191.2552,046
249151.7.192.0/21151.7.192.1 to 151.7.199.254151.7.199.2552,046
250151.7.200.0/21151.7.200.1 to 151.7.207.254151.7.207.2552,046
251151.7.208.0/21151.7.208.1 to 151.7.215.254151.7.215.2552,046
252151.7.216.0/21151.7.216.1 to 151.7.223.254151.7.223.2552,046
253151.7.224.0/21151.7.224.1 to 151.7.231.254151.7.231.2552,046
254151.7.232.0/21151.7.232.1 to 151.7.239.254151.7.239.2552,046
255151.7.240.0/21151.7.240.1 to 151.7.247.254151.7.247.2552,046
256151.7.248.0/21151.7.248.1 to 151.7.255.254151.7.255.2552,046

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.